no 1 he Irish Naturalist. [May^ 



Fern), iu Polypodium (Polypody), in Athyrium (Lady Fern), 

 the many species of Asplcninm (Spleenwort), in Ceterach (Scale 

 Fern), Scolopcndriicm (Hart's-tongue), Cystoptcris (Bladder 

 Fern), Ptcris (Bracken) and others, fructification is borne in- 

 differently by all the fronds, or at least by all which receive 

 a due amount of light and air. It is worthy of note that in 

 all these the fructification is found chiefly on the upper por- 

 tion of the frond, where the amount of light and air is greatest. 

 In the genus Lastrea (Buckler Ferns) we find the first differ- 

 entiation of fronds as regards the bearing of fructification. 

 In Lastrea cristata (Crested Buckler Fern) and L, Thelypteris 

 (Marsh Fern) fructification is borne by some of the fronds only. 

 These fronds stand up perfectly erect, and bear on their backs 

 abundance of sori, while the remaining fronds, whose main 

 function is the process of assimilation, are shorter, less erect, 

 and their divisions present rather broader surfaces to the light 

 than those of the fertile fronds. In Blechnum (Hard Fern) 

 this differentiation is more marked. The fertile fronds stand 

 quite erect, their segments very narrow ; the barren fronds 

 lie almost horizontally, and have much broader segments of 

 green tissue, where assimilation sufficient for the want of the 

 whole plant may be carried on. Here we may note an interest* 

 ing variety which shows that the two kinds of fronds are 

 but modifications of the same plant-structure. The form 

 known as anomalum, which may be found, for instance, about 

 Newcastle, in Co. Down, has all the fronds intermediate in 

 character. The segments are broader than in the normal 

 fertile fronds, narrower than in the barren ones; the fronds 

 all bear fructification on their upper half \ and they all rise 

 from the ground at an angle intermediate between that usually 

 made by the barren and by the fertile fronds. The Parsley 

 Fern {Cryptogramme crispa) also bears barren and fertile fronds, 

 quite distinct in appearance, the latter rising more erect than 

 the former. In the barren fronds, the pinnules are deeply cut 

 and lobed, so as to be almost again pinnate. In the fertile 

 fronds, the pinnules are narrow, undividedj recurved^ If a 

 series of plants be examined, barren fronds will be found in 

 which the pinnules are undivided, being egg-shaped, with a 

 scalloped margin. These appear to be, to use a hibernicism, 

 barren fertile fronds. The pinnules are shaped as in the 

 fertile frondSj but they prodtice no fructification, and are not 

 reflexed. 



